Life-History Trade-offs in Anurans: Effects of Reproductive Mode, Parental Care, and Maternal Body Size on Egg and Clutch Size

Abstract

The ecological and behavioral factors that modulate the trade-offs between offspring quality (egg size) and offspring number (clutch size) across species remain incompletely understood. Using PGLS, I estimated the independent and joint effects of reproductive mode, parental care, and maternal body size on egg and clutch size across 1,041 anuran species. The shared evolutionary history was controlled using a phylogenetic tree from the Open Tree of Life (OTL). A significant negative egg size and clutch size trade-off was detected in four of the reproductive modes. For parental care, results showed that all three types are associated with larger eggs and smaller clutches. Furthermore, the analysis shows that maternal body size (SVL) was a significant predictor of clutch size but is not associated with egg size. In joint models, the male and female parental care types retained significant independent effects on both traits, even after controlling for reproductive mode. Bi-parental care, on the other hand, became non-significant on both traits. In the full model, in which all predictors were combined, male and female care types retained significant positive effects on egg size, while biparental care remained non-significant. For clutch size, all three care types are significant. In conclusion, reproductive mode is strongly associated with the ecological conditions that shape the trade-off between egg and clutch size in anurans. Parental care, on the other hand, modifies the investment patterns of anurans to address the constraints present within their reproductive modes. Lastly, maternal body size shows that larger anuran females produce more eggs but do not invest more in each one.